We are investigating the toxic effects of drugs and metabolic poisons on the corneal endothelium. Techniques used for study include autoradiography with labeled lucine, scanning electron microscopy, transmission electron microscopy, and in vitro perfusion with the specular microscope. Time lapse cinematography is also used to follow morphologic changes seen with the specular microscope. Common antibiotics used in clinical practice are being tested. Additional studies on endothelial cells in tissue culture are being done to determine minimum toxic dose as well as characteristics of morphologic and ultrastructural changes. Effects of injury to the eye are being investigated. Osmolarity and pH changes associated with injury are being studied. The general goal is to determine a test or set of criteria by which endothelial function can be measured and cell susceptibility to drugs and trauma can be predicted.